<?php

/**
 * CCaptchaAction class file.
 *
 * @author Qiang Xue <qiang.xue@gmail.com>
 * @link http://www.yiiframework.com/
 * @copyright 2008-2013 Yii Software LLC
 * @license http://www.yiiframework.com/license/
 */

/**
 * CCaptchaAction renders a CAPTCHA image.
 *
 * CCaptchaAction is used together with {@link CCaptcha} and {@link CCaptchaValidator}
 * to provide the {@link http://en.wikipedia.org/wiki/Captcha CAPTCHA} feature.
 *
 * You must configure properties of CCaptchaAction to customize the appearance of
 * the generated image.
 *
 * Note, CCaptchaAction requires PHP GD2 extension.
 *
 * Using CAPTCHA involves the following steps:
 * <ol>
 * <li>Override {@link CController::actions()} and register an action of class CCaptchaAction with ID 'captcha'.</li>
 * <li>In the form model, declare an attribute to store user-entered verification code, and declare the attribute
 * to be validated by the 'captcha' validator.</li>
 * <li>In the controller view, insert a {@link CCaptcha} widget in the form.</li>
 * </ol>
 *
 * @property string $verifyCode The verification code.
 *
 * @author Qiang Xue <qiang.xue@gmail.com>
 * @package system.web.widgets.captcha
 * @since 1.0
 */
class CCaptchaAction extends CAction
{
    /**
     * The name of the GET parameter indicating whether the CAPTCHA image should be regenerated.
     */
    const REFRESH_GET_VAR = 'refresh';
    /**
     * Prefix to the session variable name used by the action.
     */
    const SESSION_VAR_PREFIX = 'Yii.CCaptchaAction.';
    /**
     * @var integer how many times should the same CAPTCHA be displayed. Defaults to 3.
     * A value less than or equal to 0 means the test is unlimited (available since version 1.1.2).
     */
    public $testLimit = 3;
    /**
     * @var integer the width of the generated CAPTCHA image. Defaults to 120.
     */
    public $width = 120;
    /**
     * @var integer the height of the generated CAPTCHA image. Defaults to 50.
     */
    public $height = 50;
    /**
     * @var integer padding around the text. Defaults to 2.
     */
    public $padding = 2;
    /**
     * @var integer the background color. For example, 0x55FF00.
     * Defaults to 0xFFFFFF, meaning white color.
     */
    public $backColor = 0xFFFFFF;
    /**
     * @var integer the font color. For example, 0x55FF00. Defaults to 0x2040A0 (blue color).
     */
    public $foreColor = 0x2040A0;
    /**
     * @var boolean whether to use transparent background. Defaults to false.
     */
    public $transparent = false;
    /**
     * @var integer the minimum length for randomly generated word. Defaults to 6.
     */
    public $minLength = 6;
    /**
     * @var integer the maximum length for randomly generated word. Defaults to 7.
     */
    public $maxLength = 7;
    /**
     * @var integer the offset between characters. Defaults to -2. You can adjust this property
     * in order to decrease or increase the readability of the captcha.
     * @since 1.1.7
     **/
    public $offset = -2;
    /**
     * @var string the TrueType font file. Defaults to SpicyRice.ttf which is provided with the Yii release.
     * Note that non-free Duality.ttf has been changed to open/free SpicyRice.ttf since 1.1.14.
     */
    public $fontFile;
    /**
     * @var string the fixed verification code. When this is property is set,
     * {@link getVerifyCode} will always return this value.
     * This is mainly used in automated tests where we want to be able to reproduce
     * the same verification code each time we run the tests.
     * Defaults to null, meaning the verification code will be randomly generated.
     * @since 1.1.4
     */
    public $fixedVerifyCode;
    /**
     * @var string the graphic extension that will be used to draw CAPTCHA image. Possible values
     * are 'gd', 'imagick' and null. Null value means that fallback mode will be used: ImageMagick
     * is preferred over GD. Default value is null.
     * @since 1.1.13
     */
    public $backend;

    /**
     * Runs the action.
     */
    public function run()
    {
        if (isset($_GET[self::REFRESH_GET_VAR]))  // AJAX request for regenerating code
        {
            $code = $this->getVerifyCode(true);
            echo CJSON::encode(array(
                'hash1' => $this->generateValidationHash($code),
                'hash2' => $this->generateValidationHash(strtolower($code)),
                // we add a random 'v' parameter so that FireFox can refresh the image
                // when src attribute of image tag is changed
                'url' => $this->getController()->createUrl($this->getId(), array('v' => uniqid())),
            ));
        } else
            $this->renderImage($this->getVerifyCode());
        Yii::app()->end();
    }

    /**
     * Generates a hash code that can be used for client side validation.
     * @param string $code the CAPTCHA code
     * @return string a hash code generated from the CAPTCHA code
     * @since 1.1.7
     */
    public function generateValidationHash($code)
    {
        for ($h = 0, $i = strlen($code) - 1; $i >= 0; --$i)
            $h += ord($code[$i]);
        return $h;
    }

    /**
     * Gets the verification code.
     * @param boolean $regenerate whether the verification code should be regenerated.
     * @return string the verification code.
     */
    public function getVerifyCode($regenerate = false)
    {
        if ($this->fixedVerifyCode !== null)
            return $this->fixedVerifyCode;

        $session = Yii::app()->session;
        $session->open();
        $name = $this->getSessionKey();
        if ($session[$name] === null || $regenerate) {
            $session[$name] = $this->generateVerifyCode();
            $session[$name . 'count'] = 1;
        }
        return $session[$name];
    }

    /**
     * Validates the input to see if it matches the generated code.
     * @param string $input user input
     * @param boolean $caseSensitive whether the comparison should be case-sensitive
     * @return boolean whether the input is valid
     */
    public function validate($input, $caseSensitive)
    {
        $code = $this->getVerifyCode();
        $valid = $caseSensitive ? ($input === $code) : strcasecmp($input, $code) === 0;
        $session = Yii::app()->session;
        $session->open();
        $name = $this->getSessionKey() . 'count';
        $session[$name] = $session[$name] + 1;
        if ($session[$name] > $this->testLimit && $this->testLimit > 0)
            $this->getVerifyCode(true);
        return $valid;
    }

    /**
     * Generates a new verification code.
     * @return string the generated verification code
     */
    protected function generateVerifyCode()
    {
        if ($this->minLength > $this->maxLength)
            $this->maxLength = $this->minLength;
        if ($this->minLength < 3)
            $this->minLength = 3;
        if ($this->maxLength > 20)
            $this->maxLength = 20;
        $length = mt_rand($this->minLength, $this->maxLength);

        $letters = 'bcdfghjklmnpqrstvwxyz';
        $vowels = 'aeiou';
        $code = '';
        for ($i = 0; $i < $length; ++$i) {
            if ($i % 2 && mt_rand(0, 10) > 2 || !($i % 2) && mt_rand(0, 10) > 9)
                $code .= $vowels[mt_rand(0, 4)];
            else
                $code .= $letters[mt_rand(0, 20)];
        }

        return $code;
    }

    /**
     * Returns the session variable name used to store verification code.
     * @return string the session variable name
     */
    protected function getSessionKey()
    {
        return self::SESSION_VAR_PREFIX . Yii::app()->getId() . '.' . $this->getController()->getUniqueId() . '.' . $this->getId();
    }

    /**
     * Renders the CAPTCHA image based on the code using library specified in the {@link $backend} property.
     * @param string $code the verification code
     */
    protected function renderImage($code)
    {
        if ($this->backend === null && CCaptcha::checkRequirements('imagick') || $this->backend === 'imagick')
            $this->renderImageImagick($code);
        else if ($this->backend === null && CCaptcha::checkRequirements('gd') || $this->backend === 'gd')
            $this->renderImageGD($code);
    }

    /**
     * Renders the CAPTCHA image based on the code using GD library.
     * @param string $code the verification code
     * @since 1.1.13
     */
    protected function renderImageGD($code)
    {
        $image = imagecreatetruecolor($this->width, $this->height);

        $backColor = imagecolorallocate($image,
            (int)($this->backColor % 0x1000000 / 0x10000),
            (int)($this->backColor % 0x10000 / 0x100),
            $this->backColor % 0x100);
        imagefilledrectangle($image, 0, 0, $this->width, $this->height, $backColor);
        imagecolordeallocate($image, $backColor);

        if ($this->transparent)
            imagecolortransparent($image, $backColor);

        $foreColor = imagecolorallocate($image,
            (int)($this->foreColor % 0x1000000 / 0x10000),
            (int)($this->foreColor % 0x10000 / 0x100),
            $this->foreColor % 0x100);

        if ($this->fontFile === null)
            $this->fontFile = dirname(__FILE__) . '/SpicyRice.ttf';

        $length = strlen($code);
        $box = imagettfbbox(30, 0, $this->fontFile, $code);
        $w = $box[4] - $box[0] + $this->offset * ($length - 1);
        $h = $box[1] - $box[5];
        $scale = min(($this->width - $this->padding * 2) / $w, ($this->height - $this->padding * 2) / $h);
        $x = 10;
        $y = round($this->height * 27 / 40);
        for ($i = 0; $i < $length; ++$i) {
            $fontSize = (int)(rand(26, 32) * $scale * 0.8);
            $angle = rand(-10, 10);
            $letter = $code[$i];
            $box = imagettftext($image, $fontSize, $angle, $x, $y, $foreColor, $this->fontFile, $letter);
            $x = $box[2] + $this->offset;
        }

        imagecolordeallocate($image, $foreColor);

        header('Pragma: public');
        header('Expires: 0');
        header('Cache-Control: must-revalidate, post-check=0, pre-check=0');
        header('Content-Transfer-Encoding: binary');
        header("Content-Type: image/png");
        imagepng($image);
        imagedestroy($image);
    }

    /**
     * Renders the CAPTCHA image based on the code using ImageMagick library.
     * @param string $code the verification code
     * @since 1.1.13
     */
    protected function renderImageImagick($code)
    {
        $backColor = $this->transparent ? new ImagickPixel('transparent') : new ImagickPixel(sprintf('#%06x', $this->backColor));
        $foreColor = new ImagickPixel(sprintf('#%06x', $this->foreColor));

        $image = new Imagick();
        $image->newImage($this->width, $this->height, $backColor);

        if ($this->fontFile === null)
            $this->fontFile = dirname(__FILE__) . '/SpicyRice.ttf';

        $draw = new ImagickDraw();
        $draw->setFont($this->fontFile);
        $draw->setFontSize(30);
        $fontMetrics = $image->queryFontMetrics($draw, $code);

        $length = strlen($code);
        $w = (int)($fontMetrics['textWidth']) - 8 + $this->offset * ($length - 1);
        $h = (int)($fontMetrics['textHeight']) - 8;
        $scale = min(($this->width - $this->padding * 2) / $w, ($this->height - $this->padding * 2) / $h);
        $x = 10;
        $y = round($this->height * 27 / 40);
        for ($i = 0; $i < $length; ++$i) {
            $draw = new ImagickDraw();
            $draw->setFont($this->fontFile);
            $draw->setFontSize((int)(rand(26, 32) * $scale * 0.8));
            $draw->setFillColor($foreColor);
            $image->annotateImage($draw, $x, $y, rand(-10, 10), $code[$i]);
            $fontMetrics = $image->queryFontMetrics($draw, $code[$i]);
            $x += (int)($fontMetrics['textWidth']) + $this->offset;
        }

        header('Pragma: public');
        header('Expires: 0');
        header('Cache-Control: must-revalidate, post-check=0, pre-check=0');
        header('Content-Transfer-Encoding: binary');
        header("Content-Type: image/png");
        $image->setImageFormat('png');
        echo $image;
    }
}